The Duke of Cambridge has spoken for the first time of his feelings about fatherhood, and of sleepless nights with his son, Prince George.

In his first inteview since his son's birth on 22 July, he told CNN that the third-in-line to the throne was "a little bit of a rascal".

"He either reminds me of my brother or me when I was younger, I'm not sure, but he's doing very well at the moment."

"He's growing quite quickly actually. But he's a little fighter. He wriggles around quite a lot and he doesn't want to go to sleep that much."

William, 31, admitted that his wife, the Duchess of Cambridge, took on the lions share of the night-time interruptions and was doing "a fantastic job".

In the interview, recorded before he returned to work recently, he said he was looking forward to going back to his job as a Royal Airforce search-and-rescue pilot in order to catch up on sleep.

He told interviewer Max Foster: "Well, as a few fathers might know, I'm actually quite looking forward to going back to work [to] get some sleep. So I'm just hoping the first few shifts I go back I don't have any night jobs."

Reflecting on how fatherhood had changed him, he said: "The last few weeks for me have been a very different emotional experience, something I never thought I would feel myself. And I find, again it's only been a short period, but a lot of things affect me differently now."

Speaking of the moment he and his wife introduced George to the public on the steps of the Lindo wing at St Mary's hospital in Paddington, he said: "I think more shock was the feeling I felt, but I was on such a high anyway, and so was Catherine, about George that really we were happy to show him off to whoever wanted to see him.

"As any new parent knows, you're only too happy to show off your new child and, you know, proclaim that he is the best looking or the best everything. It's nice that people want to see George. I'm just glad he wasn't screaming his head off the whole way through."

Talking about having to secure his son in a car seat in front of the massed ranks of photographers, he said: "Believe, me it wasn't my first time and I know there's been some speculation about that. I had to practice, I really did. I was terrified it was going to fall off or the door wasn't going to close properly. So I had actually practised with that seat, but only once before."

He was asked about the decision for him, rather than a chauffeur, to drive his wife and son away from the hospital, and said: "I am as independent as I want to be, same as Catherine and Harry. We've all grown up differently to other generations and I very much feel if that I can do it myself, I want to do it myself.

"There are times where you can't do it yourself and the system takes over, or it's appropriate to do things differently. But I think driving your son and your wife away from hospital was really important to me.

"For me, Catherine and now little George are my priorities - and Lupo," he said. referencing the couple's cocker.

Speaking of his Tusk Trust campaign to save endangered species in Africa, William said he hoped to encourage his son to take an interest, as his father Prince Charles had encouraged him.

"I'll have toy elephants and rhinos around the room," he said. "We'll cover it in lots of bushes and things like that, make him grow up as if he's in the bush.

"At the moment, the only legacy I want to pass on to him is to sleep more and maybe not have to change his nappy so many times." The interview will be broadcast in full on CNN next month.